Rossi A, Santoro M G
Institute of Experimental Medicine, CNR, Rome, Italy.
Biochem J. 1995 Jun 1;308 ( Pt 2)(Pt 2):455-63. doi: 10.1042/bj3080455.
Prostaglandins of the A type (PGA) induce the synthesis of 70 kDa heat shock proteins (hsp70) in a large variety of mammalian cells. Induction of hsp70 has been associated with a cytoprotective effect of PGA1 after virus infection or thermal injury. In the present report we provide evidence that, in murine myoblasts, PGA1 is not able to induce hsp70 expression, whereas it increases the synthesis of the constitutive protein, hsc70, and dramatically induces the synthesis of a 32 kDa protein (p32). The p32 protein has been identified as haem oxygenase. PGA1 acts at the transcriptional level by inducing haem oxygenase mRNA synthesis, and the signal for induction appears to be associated with decreased intracellular GSH levels. Haem oxygenase, a low-molecular-mass stress protein induced in mammalian cells by oxidant stress, is known to be part of a general inducible antioxidant defence pathway. The fact that prostaglandin synthesis is stimulated in muscle during contraction and in the heart in response to ischaemia raises the possibility that induction of haem oxygenase by PGA in myoblasts could be part of a protective mechanisms in operation during stress and hypoxia.
A 型前列腺素（PGA）可在多种哺乳动物细胞中诱导 70 kDa 热休克蛋白（hsp70）的合成。hsp70 的诱导与病毒感染或热损伤后 PGA1 的细胞保护作用有关。在本报告中，我们提供的证据表明，在小鼠成肌细胞中，PGA1 不能诱导 hsp70 的表达，而它会增加组成型蛋白 hsc70 的合成，并显著诱导一种 32 kDa 蛋白（p32）的合成。p32 蛋白已被鉴定为血红素加氧酶。PGA1 通过诱导血红素加氧酶 mRNA 的合成在转录水平发挥作用，诱导信号似乎与细胞内谷胱甘肽水平降低有关。血红素加氧酶是一种在哺乳动物细胞中由氧化应激诱导产生的低分子量应激蛋白，已知是一般诱导性抗氧化防御途径的一部分。在肌肉收缩期间以及心脏对缺血作出反应时，前列腺素合成会受到刺激，这一事实增加了 PGA 在成肌细胞中诱导血红素加氧酶可能是应激和缺氧期间运行的保护机制一部分的可能性。
